"Becky Shaw" is the kind of play that reminds us why we go to theater in the first place: to see people who are just like us, only much more interesting.They've got our issues — relationship struggles, self-esteem shortages, crazy parents — but they're sharper and wittier than us, more fun to be around than, say, our own friends.Gina Gionfriddo's play, quirky, compel...